Fuel Injector Adjustment: Troubleshooting & Help!

To all TDI/ESP experts,

After experiencing cold start problems, I tried to adjust my fuel injection pump (2.5 TDI) using the VAG-Com diagnostic tool, specifically the measurement block 08, and the TDI graph. The tool indicated that the injection timing was too early (pump set with locking mechanism and dowel). So, I adjusted the timing belt wheel (camshaft) counterclockwise. The result was that the injection timing was within range, but still too early. The engine coolant only reached 90°C after a 20km highway drive, the fuel temperature was 150°C, and the injection start was at 55 (values from the TDI graph). If I rotate the timing wheel a little further, the engine won't start. So, I can't adjust it to a later timing. I checked the crankshaft and camshaft using the locking mechanisms. When the pump is set with the locking mechanism and dowel, the engine runs loudly, misfires, and doesn't reach its maximum speed (the TDI graph indicates too early timing). Could the problem be related to the static alignment of the crankshaft and camshaft, and how can I check this using VAG-Com?
Can I make any adjustments to the software (initial quantity setting) of the pump?

Best regards,
Rainer Frank.

Note: Audi A6 2.5 TDI (AFB) Tiptronic, 120,000 km.
The following parts were replaced: both temperature sensors, glow plugs, diesel filter, crankcase ventilation system, turbocharger, timing belt, serpentine belt, idler pulleys, water pump, and fuel injection pump.

Regarding the injectors and V6 engine, what about the NW (narrowband sensor), hydros (hydraulic lifters), and injectors? What value does it show during the base setting (early/late)? It should be around 2 +/- 2 (this value is more informative than the TDI graph, which is only available in newer versions for the V6). It's not as problematic if the temperature barely reaches 90°C, but it should easily exceed 80°C. I once had a faulty thermostat; it couldn't reach above 75°C.

My device always reads a static value between 1 and 3, closer to 2, not exactly 2. Is the belt tension from the ESP correct (are the markings aligned, even after tightening the pulley)?

Hello Mr. Antje,

I'm not sure about the NW, hydros, or nozzles; they haven't been checked. However, the car was running well before the timing belt and water pump were replaced, and it didn't have any cold start problems at that time.
Is the timing mark on the tensioner that important? After all, you lock the camshaft, right?
Pump with a flat disc measuring 39x4.5 mm and a pin with a diameter of 6 mm.
TDIGraph only works with newer models, so it won't work with my 1999 A6. If I set the injection timing to 1° BTDC, the car starts poorly and runs badly, as described above.

Best regards, Rainerfrank.

Rainerfrank wrote:

1) I'm not sure about the NW, Hydros, and nozzles; they haven't been checked, but the car ran well before the timing belt and water pump were replaced, and it didn't have any cold start problems. 2) Is the marking of the tensioner that important? After all, the camshaft and pump are locked with plate 39x4.5 and pin D=6 mm. 3) TDIGraph only works with newer models, so it won't work with my 1999 A6? If I set the injection timing to 1° BTDC, the car starts poorly and runs poorly, as described above.

1) Could you take a look? It probably won't be the cause of the starting problem, but it might make the engine run a little rougher.
2) Yes, the crankshaft is secured with a dowel. The camshaft (2x) is secured with a ruler. The VP44 is secured with a 6mm dowel. Then, align the "impeller" on the camshaft so that the screws are approximately centered within the holes when the belts are tight. Belt tension is important. Both "arrows" on the tensioner should be aligned vertically. Hold the tensioner with an Allen key and tighten it securely with a socket wrench attachment. Briefly turn the engine over; all locking mechanisms must still be in place. Then, dynamically adjust the vehicle to 2° not (before top dead center), as accurately as possible, at an engine speed above 85° (likely referring to a temperature reading). If you rotate the impeller on the camshaft clockwise, you are advancing the pump's timing. If it shows 1°, you need to rotate it 1° counterclockwise.
3) No. The TDI-Graph software works with all VP44 V6 engines (AFB/AKN/AKE), but only the V6 engines are included in the current software version. Older software versions only support 4- and 5-cylinder engines, as far as I know. If you can select the AFB engine code, it should work.

Could it be that your pump is drawing in air? That's the only way I can reconcile the changed behavior with the work that's been done, assuming the pump is okay and the valve timing is correct.

If it's drawing air at night, it will also be difficult to start in the morning. Check the clear hose (leading to the VP44 pump) when you start it in the morning.

Hello Mr. Antje,

Where is the injection timing displayed in VAG-Com? Is it under measuring block 08, value 2, 3, or 4?
There is no air in the system, and the bubble in the clear tubing is approximately 0.5mm in size the next day.
Do you need to tension the timing belt when adjusting the valve timing and tightening the camshafts, or is one rotation enough until the tensioner engages?
"I tightened the tensioner. I attached the rulers to the camshafts, then removed the camshaft gears, rotated the crankshaft once clockwise, and locked it with a pin. Then I reattached the camshafts with screws. Was that okay?"

First, I will check the belt tensioner, then the fuel vent, and the oil lines for leaks (starting with the fuel cap open).

Best regards, Rainerfrank[/img].

Just for information, my AFB 2.5 TDI engine was running on two cylinders and now starts well after I increased the preheating time.

Rainerfrank wrote:

1) Where is the injection timing displayed in VAG-Com? Is it under measuring block 08, value 2, 3, or 4? 2) When adjusting the valve timing and tightening the camshafts, is it necessary to tension the timing belt, or is one revolution sufficient until the tensioner engages? "I tightened the tensioner. I attached the rulers to the camshafts, then removed the camshaft gears, rotated the crankshaft once clockwise, and locked it with a pin. Then I reattached the camshafts with screws. Was that okay?"

1) Basic setting for MWB 4. Where on earth did you get your 1° from?
2) Excuse me? Did the KW spin out with the front wheels removed?

Loosen the NW (narrow-profile) pulleys slightly, ensure all locking mechanisms are engaged, then use the hydraulic tensioner with 15Nm to assist in tightening. Tighten the NW pulleys securely. Then, lock the pump and NW pulleys, place the timing belt on the pump, center the pump pulley and lightly screw it in. Tension the timing belt on the pump, tighten the pump pulley, and rotate the crankshaft 2 times by 360 degrees. Then, re-engage all locking mechanisms.

A current VAG-COM version should display the following data when the basic settings are active...

Quote:

B004,0,Start of injection. B004,1,Engine speed, (G28), Target value (idle): 740...840 RPM Target value (full load): 3800...4200 RPM B004,2,Injection start, Range: early/late. B004,3,Injection Start Timing, (Actual Value), Setpoint (late): 0.0...4.0 °CA BTDC (Crank Angle Before Top Dead Center)\nSetpoint (early): minimum 12.0 °CA BTDC B004,4,Valve for,Injection start,Value range: 0.0...100.0 % Target value (late): 100.0 %

Does that help?

Hello everyone,

I have now adjusted the ESP (2° after TDC). It turns out the problem was with the tensioner pulley for the ESP timing belt; the indicators weren't aligned correctly and seemed to have shifted. (It was too tight). I'm sure I adjusted it correctly, but after the engine ran, the tensioner must have readjusted itself. So, after tightening the belt, always rotate the engine several times and then check the tension again after the engine has been running.
I had the injection timing (1°) read out by the workshop because I'm new to using VAG-Com. Yes, I rotated the crankshaft one revolution, with the timing belt pulleys slightly loosened but not completely detached, which fully pre-tensioned the tensioner.

Yes, the description of measurement block 4 was helpful, now I can check it myself. Thank you very much! Where can I get a complete documentation of the VAG-Com measurement values?

Starting problems still exist, and it might help to increase the starting fuel quantity setting, or, as mserge writes, increase the preheating time.

Best regards, Rainerfrank.

Rainerfrank wrote:

Where can I find a complete documentation of the VAG-Com measurement values?

Normally, it's in the VC distribution provided by the distributor you purchased your VC system from.

First, are you now satisfied with the noise level? Are you now "only" experiencing starting problems?

I don't have any air bubbles in the supply line; I've already checked that. Otherwise, you should check the glow plugs.

Rainerfrank wrote:

Yes, I had rotated the crankshaft one revolution, with the timing belt pulleys slightly loosened but not detached, which caused the tensioner to be fully pre-tensioned.

The NWs are installed and in place while you turn the KW. This means that some valves are open. The pistons will hit the valves if you over-rev it. Please avoid doing that next time.

Hello Mr. Antje,

The background noise is now okay. I'm "just" still having cold start problems.
Okay, I just checked my fuel injectors.

MWB AZ Group 13.
(Cylinders 3 and 1) Engine idling.
Measurement block 13: 1.25 mg/H, 0.69 mg/H.

MWB AZ Group 14.
(Cylinders 6, 4, 5) Engine idling.
Measurement data block 14: -1.33 mg/H, 1.34 mg/H, 1.53 mg/H.

Cylinder 5 is outside of the tolerance range, which could indicate a problem with compression (at 115,000 km?), what can I do about it?
"What I don't understand is that the engine had a good cold start before the timing belt and water pump were replaced, and it only reached a top speed of 200 km/h. Now, it starts poorly and reaches a top speed of 210 km/h."
I assume the initial flow rate of the old pump was higher; otherwise, I can't explain it.

Best regards, Rainerfrank.

Rainerfrank wrote:

NW, Hydros, and nozzles, I don't know if they are checked,

Someone on Motortalk is writing under the same name as you and is experiencing the same problem.
Yes, I still have the NW (presumably referring to a wear indicator). The workshop master said it's not as bad as it looks, and they only replace them when the wear exceeds 0.5 mm or more.

christians wrote:

Rainerfrank wrote: NW, Hydros, and nozzles, I don't know if they have been checked, . Someone on Motortalk is writing under the same name as you and is experiencing the same problem. Yes, I still have the NW (presumably referring to a measurement or component). The workshop master said it's not as bad as it looks, and they only replace them if the wear exceeds 0.5 mm or more.

"Yes, yes, they also tried to tell me that the 0.5 mm was okay. But if the camshafts are wearing down, who can tell me that's healthy for the rest of the engine? After that, you'll have turbocharger damage, then the bearings will fail, and so on. A camshaft that's starting to wear out should be scrapped, because wear inside the engine is very bad, regardless of the filter. That's why my camshafts were replaced at 135,000 km *before* I had to report any damage, and only because I asked. The workshop didn't want to replace them!"
I doubt that's the reason why your engine isn't starting well. It's more likely to be issues with the fuel injectors, preheating time, injection timing, starter motor speed, etc.

Hello everyone,

Yes, I also visit other forums (just like you do, though), and that shouldn't be a bad thing, right?
The issue with the camshafts cannot be the cause of the poor cold starting behavior.
"It started well before the ESP (October 06) and timing belt were replaced."
However, it was warmer (in April), but the cold start problems were still present even at 15°C.
which allows me to rule out the heating system.

Okay, I'm signing off for now. If necessary, I'll use my second car during the holidays.
use.

Best regards, Rainerfrank.

I'm not concerned about visiting other forums, but rather about the fact that you've made obviously incorrect statements here. If you're seeking help, you should leave the evaluation of all the facts to those who are trying to assist you. The more information you withhold, the less likely it is that someone will be able to identify the cause of your problem.